Blower



March 1, 1938. E. c. FANNING 2,109,742

BLOWER Filed Sept. 17, 1935 FIE3 .J

INVENTOR.

f/T0// C 57/7/7079 ATTORNEY.

considerable extent. refinements, discharge of air from a conventional.

Patentecl'Majr. -1, 1938 PATENT OFFICE BLOWER .Erroll crFanningrBerkeley, Calif., assignmto Atlas Heating .11 Ventilating Co. Ltd., San Francisco, Calif.,-a corporation of California Application September 1', 1935, Serial No. 40,915 2 Claims. (CL 230-232 v This invention relates generally to blowers such as are employed in various appliances to secure a forced draft or circulation of air. It has particular application to installations where'noise is objectionable, as for example where the blower is employed for use with hot air furnaces, and ventilating or air conditioning equipment.

Many refinements have been made in blower constructions, to minimize noise and vibration. For example, rubber mounted bearings and motors, together with'carefully designed low speed rotors, have alleviated the problem of noise to a However, even with such type of blower is accompanied by an objectionable swishing noise. By a conventional type of blower,

' I have reference to one having a sheet metal housing contoured in accordance with an Archimedes spiral. While the swishing noise may orlgi nate in part through turbulent fiow of air from the rotor blades, I attribute it mainly to rapid fiow of air into contact with the inner peripheral surface of the housing. Such noise is particularly objectionable in hot air furnaces or in air conditioning equipment, in that it travels along the air stream and is projected into the room being heated or ventilated.

'It is an object of the present invention to. pro

vide a simple type of blower which will substanthe following description, in which the preferred:

tially entirely minimize the objectionable swishing noise, referred to above.

' Further objects of the invention will appear in embodiments of the invention have been set forth in detail in conjunction with the accompanying drawing. v

Referring to the drawing: v Fig. 1 is a side elevational view, illustrating a I blower constructed in accordance with the presline 2-2 of Fig.1.

Fig; 3 is an enlarged cross sectional detail, taken along the line 3-3 of Fig. 2.

Fig. 4 is a cross sectional view similar to Fig. 2 but showing a modified form. r

Fig. 5 is a cross sectional view taken along the line 5-4 of Fig. 4.

The blower illustrated in the drawing consists of a housing It, formed of suitable material such as sheet metal, in conjunction with a rotor ii. The rotor is of course carried by suitable journals, and isv connected to an electric motor or like source of power. The side walls {if of the housing are provided with air inlet openings [3, while noted that the housing is contoured in accordance with an Archimedes spiral, with the wall il of the discharge conduit I being a tangential extension of the peripheralhousing wall it.

The means provided for substantially entirely suppressing the swishing noise, which is deemed largely caused by fiow of air along the inner surface of walls i1 and I8, consists of a baiiie l8. As will be evident from Figs. 2 and 3, this baffle I9 is of sufilcient length to extend across the wall l1, and it also extends upwardly from this wall a substantial distance into the stream of discharging air. Instead of having the general plane of this bailie disposed at right angles to the plane of wall i1, it is preferable to incline it against the stream of air, as illustrated in Fig. 3. While the location of baflie l9 may vary, it has been found convenient to attach it to the forward edge of the wall IT, as shown in Fig. -3.

Without wishing to confine myself to a precise theory of operation, the baflie described above appears to function as follows: When the blower is in operation it has been observed that a dead air space 2| is created in front of the baiile l8, which extends for a substantial distance into the blower housing and along the peripheral wall of the same. This dead air space serves as a cushion, to absorb and dampen out relatively high frequency noises originating in the air fiow, and to also blanket a substantial portion of the peripheral housing wall to minimize rapid flow of air across the surface of the same. Likewise the baiiie serves to reflect back into the dead air space, high frequency noises, which, in the absence of such a battle, appear to be propagated in a strata of the discharging air stream adjacent the wall 11. The net result is that propagation of the undesired high frequency swishing noise through'the conduit I6, is substantially entirely suppressed or minimized.

It will be evident that for a given speed oi. operation of the rotor, the presence of bailie I! will slightly decrease the capacity pf the blower. Such decrease in capacity can be compensated for by a slightly increased size of housing, to

afford a larger cross sectional area for the dispacity.

than would be occasioned without use of the baiile, and with the blower operating at reduced ca- As explained above, the majority of the noise which it is desired to suppress, appears to be confined to a strata of the discharging air stream, adjacent the wall l1. However, a certain amount of additional noise can be suppressed by the addition oi. side baiiles 22, as shown in Figs. 4 and 5. These side bafiies function in a manner similar to baflle l9, except that they create dead air spaces extending along the side walls of the housing.

It will be evident that the means which I have provided is quite simple in construction, and necessitates only slight additional expensein the construction of the blower. However, the results obtained constitute a remarkable improvement in the attainment of noiseless operation.

I claim:

1. In a blower of the character described, a spirally contoured conduit housing having a discharge conduit, one wall of the conduit being a tangential continuation oithe outer peripheral wall of the housing, a rotor disposed within said housing, and means positioned within said conduit for minimizing airflow noise, said means comprising a baiile extending from said one wall into the stream of air discharging through the conduit, said baiiie being inclined against the air flow and having a length sufiicient to extend across said one wall.

2. In a blower of the character described, a spirally contoured conduit housing having a discharge outlet, one wall of the outlet being a tangential continuation of the outer peripheral wall of the housing, a rotor disposed within said a housing, and means positioned within said conduit for minimizing airflow noise, said means comprising a baflie extending from said one wall into the stream '01 air discharging through the conduit, said baflle being inclined against the air flow at an angle of at least about 45 and having a length sufiicient to extend across said one wall.

ERRQLL c. ANNING. 

